title: Self-aligned U-gate carbon nanotube field-effect transistor with extremely small parasitic capacitance and drain-induced barrier lowering.
abstract: A novel self-aligned U-gate structure for carbon nanotube (CNT) field-effect transistors (FETs) is introduced and shown to yield excellent dc properties and high reproducibility that are comparable with that of the best CNT FETs based on the previously developed self-aligned device structures. In particular the subthreshold swing of the U-gate FET is 75 mV/dec and the drain-induced barrier lowering is effectively zero, indicating that the electrostatic potential of the whole CNT channel is most efficiently controlled by the U-gate and that the CNT device is a well-behaved FET. Moreover the high-frequency response of the U-gate FET is investigated, and the parasitic capacitance of the device is measured and shown to be one magnitude smaller than that of the previously developed self-aligned device structures. Direct frequency domain measurements show that the U-gate CNT FETs can operate up to 800 MHz, which is also higher than previously reported values. The large improvement in the device high-frequency behavior is largely due to the replacement of the high-κ dielectric material between the source/drain and the gate by a vacant space with κ ≈ 1, and the significant reduction in the device parasitic capacitance renders the U-gate CNT FETs promising for rf applications.
authors.affiliation: Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Ding
authors.forename: Zhenxing
authors.initials: Z
authors.lastname: Wang
authors.forename: Tian
authors.initials: T
authors.lastname: Pei
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Sheng
authors.initials: S
authors.lastname: Wang
authors.forename: Huilong
authors.initials: H
authors.lastname: Xu
authors.forename: Fei
authors.initials: F
authors.lastname: Peng
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Lian-Mao
authors.initials: LM
authors.lastname: Peng